The present invention relates to a device for slicing loaves and other bakery products, such as for example cakes and pastries. These bakery products may optionally be completely frozen, or frozen just on the outside, in particular in order to allow cutting of soft bakery products or of bakery products with a filling which is soft at room temperature, such as pies. In addition, the invention relates to a cutting-blade carrier for a device of this kind and to the cleaning of the cutting blades of a device of this kind.
A known device for slicing loaves is described in GB-1,464,604. This device is provided with two cutting-blade carriers, which are disposed one behind the other, as seen in the passage direction of the loaves. The two cutting-blade carriers are each guided in a straight line, substantially perpendicular to the passage direction of the loaves, in the frame of the device and are moved in a reciprocating manner in opposite phases.
In generally known bread-cutting devices, the cutting-blade carriers are driven with a rectilinear, reciprocating movement, which has an amplitude of between 30 and 45 millimeters and a frequency of 700 to 800 reciprocating movements per minute. Another known device has only one cutting-blade carrier, which is driven with a rectilinear, reciprocating movement which has an amplitude of 3 millimeters and a frequency of approximately 3000 reciprocating movements per minute.
In practice, the known devices have proven unsatisfactory. Particularly if the bread was baked shortly before, it adheres to the cutting blades, with the result that it is desirable, not to say necessary, to regularly remove the bread material which adheres to the cutting blades during the cutting operation. This is because bread residues adhere to the cutting blades to an ever increasing extent as the cutting blades become dirtier.
For the purpose of cleaning the cutting blades, it is generally known in the case of the devices of the large-amplitude type to provide one or more scraper members, which are disposed outside the path through the cutting device for the loaves, the cutting blades being scraped clean on moving past a cutting member. In practice, the loaves to be cut are frequently so high, approximately 15-20 centimeters as seen in the longitudinal direction of the cutting blades, that the central part of the bread-cutting length of the cutting blades does not move past one of the scraper members in these known devices, and is therefore not cleaned. In the case of the known small-amplitude device, it is impossible to clean the cutting blades in this manner during cutting of the bread.
It is also known to apply a small quantity of an edible lubricant to the cutting blades during the cutting operation, particularly when cutting bread with a low fat content. The application of lubricant can also only take place outside the path of the loaves. Owing to the considerations outlined in the preceding paragraph, it is clear that in many cases the known devices do not allow satisfactory lubrication of the cutting blades.
A further drawback of the known devices is that the cutting operation entails an undesirably high loss of bread material, owing to the formation of crumbs. The crumbs are mainly formed as a result of the contact between the sides of the cutting blades and the bread, in particular at the location of the transitions between that edge of each cutting blade which is provided with cutting formations and the substantially flat sides of this cutting blade.
The object of the present invention is to eliminate the abovementioned problems. Furthermore, the invention aims to eliminate a considerable number of other drawbacks of the known devices. These drawbacks include the fact that the known cutting-blade carriers are expensive and that exchanging a cutting-blade carrier requires a maintenance person and takes up considerable time, during which time cutting cannot take place. The present invention also aims to provide measures which improve the cleaning of the cutting blades, so that the cutting blades last longer and fewer crumbs are formed.
According to a first aspect, the present invention provides a device according to the preamble of claim 1, which preamble is based on GB-1,464,604, which device is characterized by the characterizing part of claim 1.
The characteristic part of claim 1 provides for the movement of each cutting-blade carrier to be the resultant of the low-frequency first movement, which may also be an intermittently executed movement, having a large amplitude, on the one hand, and a high-frequency, preferably continuous, second movement having a small amplitude, on the other hand.
In the preferred embodiment, the cleaning means may comprise, for example, two cleaning devices, one below and one above the path for the loaves, in which case, for example, the position of the top cleaning device is adjustable with respect to the support means for the loaves, so that the position of the top cleaning device can be matched to the height of the loaves to be cut. In a variant, only one cleaning device may be provided, for example at a short distance below the path for the loaves. The invention provides for the cutting action of the cutting blades to be effected substantially by the second movement and for the first movement to serve primarily to allow the cutting blades to move past the cleaning means over their entire bread-cutting length.
In the preferred embodiment, the effect is achieved that the cutting blades not only move in a rectilinear, reciprocating manner in the longitudinal direction of the cutting blades, as in the case of known devices, but also each cutting blade executes small loop movements with a high frequency. This loop movement is very advantageous for the cutting action of the cutting blades when cutting bread and other bakery products. The loop movement is also advantageous if the sides of the cutting blades bear against scraper surfaces of a scraper member, because in this case a type of polishing effect is achieved.
The claims describe the advantageous direction of the loop-like movement, the loaf to be cut remaining in a stable position on the support means.
The claims describe values which are advantageous in practice, the magnitude of the first amplitude being dependent substantially on the height of the loaf to be cut and on the arrangement of any cleaning means for the cutting blades. The second amplitude is preferably small.
The claims describe values which are advantageous in practice, and it should be noted that in principle the first movement does not have to be a continuous movement, but may also be a stepwise movement, since the cutting action is effected substantially by means of the second movement.
The position of the cutting formations are considerably closer together, i.e. with a finer toothing, than that which is used in the case of the known devices. The distance between the cutting formations is preferably less than the second amplitude.
In the preferred embodiment, the second drive means only have to drive the relatively lightweight cutting-blade carrier and associated holding means, without having to cover a long drive path.
The invention makes it possible for there to be only one single cutting-blade carrier present, instead of two, as in the known devices. This is possible because in the device according to the invention the bread is not dragged along by the cutting blades which move with a small amplitude and a high frequency and are preferably regularly cleaned during the cutting operation. However, a variant of the device according to the invention comprises two cutting-blade carriers which are disposed one behind the other in the passage direction of the loaves, in which case an advantageous embodiment provides for the two cutting-blade carriers each to be driven with an identical second movement, but in opposite phases, and for the two cutting-blade carriers to be driven by common first drive means providing the first movement.
According to a second aspect, the present invention provides a device for slicing loaves and other bakery products having tensioning of the blades. The known cutting-blade carriers, an example of which is described in GB-2,007,971, comprise a rectangular framework, in which the cutting blades are fixed under tensile stress. The cutting-blade carriers are of robust and strong design, in order to be able to withstand the total tensile stress in all the cutting blades. A usual tensile stress is approximately 500 N per cutting blade, so that in the case of 40 cutting blades the side bars of the framework each have to be able to withstand a compressive force of 10 kN. On the other hand, the cutting-blade carrier must be lightweight, in order to limit the acceleration and retardation forces occurring at the reciprocating-movement frequency which is required for the cutting action. In order to fulfil both demands, the known cutting-blade carriers are generally produced from expensive metal alloys, such as magnesium alloys.
The measures make possible a considerably more lightweight, and in particular a less expensive, design of the cutting-blade carrier. In the device, the cutting-blade carrier no longer serves to hold the cutting blades at the required operational tension, as has hitherto been the case, but merely as a temporary holder for the cutting blades. The cutting blades are tensioned after the cutting-blade carrier has been placed in the device, with the aid of tensioning means which form part of the cutting device. The cutting-blade carrier can therefore be designed as a lightweight and simple holder which holds the cutting blades in the desired position and can be handled as a single unit with the cutting blades held therein. As a result of this measure, it is economically possible to keep a stock of a plurality of cutting-blade carriers with cutting blades therein for a single cutting device, for example to keep a separate cutting-blade carrier, with a suitable distance between the cutting blades, for each type of bread to be cut.
The measure makes it possible to slide the cutting-blade carrier into the device transversely to the passage direction of the loaves, with the result that one cutting-blade carrier can be replaced quickly and easily with another.
The claims describe the cutting-blade carrier which can be used to realize the device of the present invention. The spacer means of the cutting-blade carrier may take many different forms, for example the form of connecting elements which are placed between the top and bottom attachment bodies and provide a low resistance to extension, for example made of plastic material. It would also be possible to provide for the spacer means to be attached in a releasable manner to the top and bottom attachment bodies and to be removed entirely after placing the cutting-blade carrier in the cutting device, if appropriate automatically using the device itself.
According to a third aspect, the present invention provides a device for slicing loaves and other bakery products having a cleaning of the blades. In bread-cutting devices, it is known to use scraper members whose slot openings are at an angle to the longitudinal direction of the cutting blades, so that on one side of the cutting blade the top edge of the slot opening forms a scraper surface, and on the other side the bottom edge forms a scraper surface which is in contact with the cutting blade. Owing to the inevitable wear to the scraper member at the location of the scraper surfaces, the contact pressure between the scraper surfaces and the cutting blade will gradually decrease, and the cleaning action is reduced. The displacement means enable one or other scraper surface alternately to be pressed against the cutting blade with an adjustable larger force, even if the scraper surfaces have already been worn away to some extent. As a result, the cutting blade is cleaned very effectively and the scraper member can still be used even if wear has taken place.
According to a fourth aspect, the present invention provides a device, which prevents contaminants scraped off a cutting blade from collecting in the slot opening in the scraper member.
Another embodiment makes it possible to combine the advantages of the devices of the 3rd and 4th aspects of the present invention with one another, with the result that very effective cleaning of the cutting blades is achieved.
According to a fifth aspect, the present invention provides a device for reducing time for exchanging blades. As has already been mentioned above, it is desirable to reduce the time required for exchanging a cutting-blade carrier. The measures according to this aspect of the present invention; contribute to reducing this time. These measures are particularly advantageous in combination with the previously described devices.
According to a sixth aspect, the present invention provides a cutting-blade carrier. In the case of the known cutting-blade carriers, all the adjustable attachment members are arranged on the top bar and all the fixed attachment members are arranged on the bottom bar of the cutting-blade carrier. However, the adjustable attachment members take up a larger space than that which is required for the fixed attachment members. The alternate arrangement allows a minimal distance between the cutting blades.
According to a seventh aspect, the invention provides a device with a provision for the scraper members which are required for scraping a set of cutting blades to be exchanged at the same time as the cutting-blade carrier, all this taking place automatically. This is possible as a result of the scraper members, of which there are usually two per set of cutting blades, already being attached beforehand temporarily to the cutting-blade carrier, and as a result of providing the cutting device with a suitably designed mechanism which, after the cutting-blade carrier has been placed in the device, grips the scraper members, moves them to their desired position and then holds them fast. If appropriate, there may be provision for the mechanism to fix the scraper members back on the cutting-blade carrier before the cutting-blade carrier is removed, so that these scraper members are removed together with the cutting-blade carrier. This design is particularly advantageous in combination with the designs of the previous devices.
According to an eighth aspect, the invention provides a device with a design of the slot openings in the scraper member prevents wear causing the scraper surfaces to wear down to recesses in the walls of the slot openings. In practice, this would make it impossible to clean a new set of cutting blades with the same scraper member, since the cutting blades also become slightly worn and therefore new cutting blades would not fit in the worn-out recesses. This measure is particularly advantageous in combination with a previous device in which the cutting blades perform a small loop-like movement in their plane.
It will be clear that the above-described aspects of the invention are advantageous by comparison with the known devices both separately and in various combinations.